BURLINGTON — The family of an unarmed man who died after being shocked by a Vermont State Police stun gun filed a federal lawsuit Wednesday as a way to hold police accountable for their actions, an attorney said.

The lawsuit, filed in U.S. District Court in Burlington, claims police used excessive force when they responded to Macadam Mason’s home in Thetford on June 20, 2012. Troopers were asked to check on his well-being by Dartmouth Hitchcock Medical Center in Lebanon.

Attorney Robert Appel was accompanied to federal court by Mason’s mother, Rhonda Taylor; her husband, Ken Taylor; and Allen Gilbert of the Vermont chapter of the American Civil Liberties Union.

“I have to say this is a very sad day, not only for Rhonda and her family but for the state of Vermont,” Appel said. “This is the only way the people of this state can hold police accountable.”

The lawsuit seeks unspecified damages, which would be used to benefit Mason’s daughter, Appel said.

State police spokeswoman Stephanie Dasaro said Wednesday it would be inappropriate to comment on pending civil litigation.

Mason’s death after being shocked in the chest by an electronic stun gun outside his home prompted the Legislature to pass a law requiring the creation of a stun gun use policy that will be adopted by police departments.

The law also says officers may use stun guns only against people who are exhibiting active aggression or who are actively resisting in ways likely to harm themselves or others.

Mason, who had a history of seizures, was suffering from what records called a mental health crisis. He was hit in the chest with the electric probe of a stun gun fired by Trooper David Shaffer after he advanced toward the trooper.

Shaffer later told investigators he feared he was going to be assaulted.

Mason collapsed and, despite efforts to revive him, was later pronounced dead. An autopsy determined Mason’s sudden cardiac death was due to “conducted electrical weapon discharge.”

The lawsuit says Mason, who suffered from mental illness, had experienced a seizure the day before and his partner had told police that after such events he needed to be left alone.

An investigation by the Vermont attorney general’s office determined no criminal charges should be filed against Shaffer.

But Appel said the burden of proof for a civil action is much less than the standard required for a criminal conviction.

“It’s relatively routine that even when people are acquitted in a criminal case ... they are still found liable in a civil suit because of the lesser standard of proof,” Appel said.